import java.util.*; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int N = sc.nextInt(); int[] w = new int[N]; for(int i = 0; i < N; i++) w[i] = sc.nextInt(); // dp[i][j]は重りiまでで和をj-10000と出来るかを表す int[][] dp = new int[N][20001]; dp[0][w[0] + 10000] = 1; dp[0][-w[0] + 10000] = 1; for(int i = 1; i < N; i++) { for(int j = 0; j < 20001; j++) { if((dp[i - 1][j - w[i]] == 1) || (dp[i - 1][j + w[i]] == 1)) dp[i][j] = 1; } } String ans = "impossible"; if(dp[N - 1][0] == 1) ans = "possible"; System.out.println(ans); } }